ARTIFICIAL PEROXIDASES 547 



Respiratory Coloring Substances. When it is recalled 

 that the color component of haemoglobin, haematin, loses its 

 peroxidase-like power when deprived of its iron by conver- 

 sion into hasmatoporphyrin, and when recalled also that 

 Gabriel Bertrand, who has devoted himself largely to the 

 study of the oxidases, has shown that the effectiveness of 

 many of these substances is related to the manganese they 

 contain, 25 the suggestion at once arises that the real point of 

 the whole oxidase problem may perhaps be found in the 

 catalytic action of metals, especially those which because of 

 their power to exist in different stages of oxidation are 

 likely to serve as oxygen carriers. It is surely not an acci- 

 dental matter that not only haemoglobin, but also many other 

 respiratory pigments which are found in the invertebrates, 

 as the echino chrome of the seaurchins, hcemerythrin, and the 

 green chlorocruorin of marine worms (cf. Vol. I of this 

 series, pp. 224, 225, Chemistry of the Tissues), contain iron; 

 and in case of the blue hcemocyanin in the blood of mollusks 

 and crustaceae, which apparently contains copper, it should 

 be recalled that salts of copper possess in a high degree the 

 ability of catalytically conveying oxygen. 26 When, too, 

 it is remembered that we know that colloidal metals 27 or 

 metals in combination with colloids are particularly active 

 in this respect, there is every reason to justify the attempt 

 to produce artificial oxidases. 



Artificial Peroxidases. Quite a number of experiments 

 have actually been presented with this end in view. 28 Thus 

 Trillat 29 found that in bringing together a salt of man- 

 ganese, an alkaline hydroxide and a colloid, an association 

 resulted which is entirely comparable to natural peroxidases. 



23 G. Bertrand and F. Medigreceanu, Compt. Rendu., 154, 1450, 1912. 



23 Cf . H. A. Colwell, Jour, of Physiol., 39, 358, 1909. 



21 Cf . C. Foa and A. Aggazzotti, Biochem. Zeitschr., 19, 1, 1909. 



"Literature upon Artificial Peroxidases: J. H. Kastle, 1. c., pp. 122-131; 

 C. Oppenheimer, Die Fermente, 3d ed., 348-351, 1909; F. Battelli and L. Stern, 

 Ergebn. d. Physiol., 12, 241-243, 1912. 



28 A. Trillat, Compt. rend., 138, 274, 1904, and earlier contributions. 



